The present invention relates to a method of fabricating a nitride semiconductor, including the step of activating a p-type impurity, and a method of fabricating a semiconductor device using the same.
Nitride semiconductors such as GaN, AlGaN mixed crystal, and AlInGaN mixed crystal have been expected as materials for forming light emitting devices allowing emission of light in a wide range from a visible region to an ultraviolet region, or materials for forming electronic devices. In particular, light emitting diodes (LEDs) using nitride semiconductors already have been available and have become a focus of attention. The realization of semiconductor lasers (LDs) using nitride semiconductors also has been reported, and such LDs have been expected to be widely applicable, for example, as a light source for an optical disk drive.
By the way, to obtain excellent characteristics of such a device, it is important to bring an electrode into desirable ohmic-contact with the semiconductor for reducing the contact resistance therebetween. In this regard, for an n-type semiconductor, since a relatively high carrier concentration of the n-type semiconductor can be ensured by doping an n-type impurity, such as silicon (Si) in the semiconductor, an electrode can be easily brought into ohmic-contact with the n-type semiconductor.
For a p-type semiconductor, however, since a p-type impurity, such as magnesium (Mg), doped in the semiconductor is bonded with hydrogen (H), the rate of activating the p-type impurity is low, and thereby the carrier concentration of the semiconductor is as low as about 1×1018 cm−3. As a result, it is difficult to bring an electrode into desirable ohmic-contact with the semiconductor, so that there arise the problems that the operational voltage is increased and the characteristics are liable to be varied.